The disclosure relates a method to determine the deformation of a web-shaped recording medium in a digital printer. Furthermore, the disclosure relates to a method to compensate for effects of the deformation of a recording medium in a printer, including compensating for effects on a print image to be printed.
A digital printer, for example an inkjet printer, may be used to print to a web-shaped recording medium. The recording medium may thereby be flexible and elastic, such as for plastic films or textiles. Upon printing to a flexible recording medium, the recording medium may deform substantially under tension. In particular, the recording medium may be substantially stretched by the web tensile force that is applied to convey the web-shaped recording medium through the printer. As a result of the stretching of the recording medium, distortions may occur of the print image that is printed onto the stretched recording medium.
To compensate for distortions of a print image, in DE 10 2009 051 197 A1 a correction method for a digital printing process was described in which the print image is adapted to the deformation of the recording medium in a printer via a calculation algorithm. The algorithm uses a deformation factor as an input value, wherein the deformation factor is determined by printing a ruler onto the recording medium and by measurement of the printed ruler by a user, or via an optical sensor. In U.S. Pat. No. 4,721,969 A, register marks are used to determine register errors, wherein the register marks are detected with CCD (Charged Coupled Device) sensors.
In the two aforementioned documents, a printed mark is used in order to determine the deformation of a recording medium. This requires a dedicated printing process for printing a marking for the determination of the deformation of the recording medium, and thus is linked with additional time and resource costs.
DE 691 14 302 T2 describes a method to monitor the lengthening of a running belt. DE 101 37 258 A1 describes a method to determine a characteristic tension/stretching line of a material web. EP 0 951 993 A1 describes a method to determine the longitudinal stretching of a paper web. DE 10 2013 214 016 A1 describes a method for correction of a print image by an extension factor. DE 10 2014 013 370 A1 describes a method for compensation of local register inaccuracies.
The exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.